If you can share one cited example of a water boil alert being issued solely because of persons not showing up to work, I’ll believe your hypothetical.
A natural disaster or pipe break that forces a water boil alert could happen any time.
Again, I am trying to understand if there is any elevated need to have bottled water at home during pandemic fear vs any other time when run-of-the-mill water boil alerts are issued.
Of course, that's the case with seasonal flu as well, which is why it's a good idea to keep water on-hand to start with.